The mechanism of action for ED pills is simple: They inhibit the PDE5 enzyme which regulates the signals responsible for the smooth muscle tissue. Some men are okay with these side effects, and find signs like facial flushing reassuring because it helps them to know the drug is working. There are many safe, reliable online services offering ED prescriptions. At the same time, the brain tells other vessels near the penis to tighten up, to keep blood in this sponge tissue — and this is what makes an erection last. Insurance can help you save even more on consultations and medications. How we source info.Place and receive your order: Once you have your prescription, you can place your order. No insurance is needed to order medications from the Optum Store after receiving your . Best Low Cost: GoodRx Fastest Delivery: Blink Health: Sesame Sign Up Now Key Specs Cost: Consultation prices vary based on the prescriber; $5 generic prescriptions Medical . About Viagra (sildenafil citrate) Viagra was the first oral ED medication, approved by the U.S. Food and Drug Administration in Viagra has been studied for more than 15 .